Gatsby Category Count

Whilst rebuilding this blog I wanted to recategorise all of the existing posts. Before doing so, I wanted to see what all of my existing categories were and how many posts I had in each category.

Using graphql and the GraphQL explorer I could run a query to group by frontmatter___category and return the total count

graphql
{
  allMarkdownRemark {
    group(field: frontmatter___category) {
      fieldValue
      totalCount
    }
  }
}